Investigating stability of orthodontics – Arch form

Blog

May, 3, 2011

By: S. Jack Burrow

Journal: American Journal of Orthodontics and Dentofacial Orthopedics 2008:134:430-438, Miner RV., published an investigation studying stability of orthodontics.

Past research has revealed that proper dental arch form is the criteria for orthodontic stability, i.e., the arch should not be constricted or expanded beyond an individual’s limit.

The objective of this study was to investigate the relationship between the dental arch form and the supporting bone.

Results – There is a large range of arch forms, i.e., there are large people and small people and the size of the dental arch is just as varied. They found a statistically significant positive relationship between dental and basal arch forms, which supports the concept of positioning teeth over the apical base. The large individual variation suggests that there is no ideal arch form that fits all sizes / individuals. Each arch (individual) has its own form so the orthodontist needs to be cognizant and shape his wire accordingly.

 Conclusions: Arch forms for each patient are individual and the orthodontist needs to position the teeth over basal bone.

 Comments: Some philosophies support the idea that a certain system or bracket will allow the orthodontist to expand the teeth beyond basal arch form limits. This research found a high correlation between dental arch form and apical base arch form which implies that if a patient is crowded  it’s not a good idea to expand the arches beyond the basal arch form… if expanded then the teeth will not be stable.  – i.e., the teeth will relapse.